As is well known by those skilled in the sealing technology leakage of the oil intended to lubricate the components of a motor in a high speed rotating machine is and continues to be a serious concern not only because of the inefficient use of the lubricant but because the escaped lubricant can be a hazard to the environment as well as being a serious problem in the operation of the rotary machine in application where the high speed machine is being utilized. The latter is a real concern in the medical environment where it is abundantly important to prevent contamination of the patient and the operating equipment that is used in surgery.
This invention has solved this problem by the use of two inventive seals that independently are unique and when placed in tandem in a lubricated ball bearing environment have proven to be 100% leak proof. According to this invention, the seals are a disk shaped made from a thermal setting material such as Teflon® and are fixedly mounted around the rotating shaft such that they are static, and one of the seals is disk shaped and mounted adjacent to a judiciously spaced seal retainer that serves to angle that seal relative to the shaft for defining a lip. The other seal is also disk shaped, and is judiciously mounted relative to the inner race of the ball bearing in the rotating machine so that the oil of an air/oil mist is slung toward the direction of the centrifugal force and the air is allowed to flow in a direction opposite to the direction of the centrifugal force so that the delta pressure across the seal will dictate the leakage of air. Both seals are made operative in situ by rotating the machine to generate sufficient heat to deform the seals and cause them to set so that it virtually allows only the air to escape while trapping the oil. These seals when mounted in tandem serve to maintain a leak proof sealing device.
An example where this invention is efficacious is where a vane motor in a pneumatic surgical motor powers a surgical drill or other medical instruments and the vane motor is supported by ball bearings. This invention locates the tandem seals downstream of the ball bearings where one of the seals is adjacent to the inner race of the ball bearing and the other is spaced axially downstream thereof. An oil/mist is utilized to flow into the vane motor to lubricate the vanes and the seals prevent the oil to leak in the mechanism that supports the drill or other surgical instruments to assure that these parts as well as the patient and the ambient do not become contaminated by leakage oil.